氟伐他汀、苯那普利对自发性高血压大鼠血管平滑肌细胞L型钙通道α1C表达的影响

Effect of Benazepril and Fluvastatin on L-type Calcium Channel α1C Expression in Vascular Smooth Muscle Cells from Spontaneously Hypertensive Rats

背景在血管平滑肌细胞(VSMC)中,L 型钙通道是提高细胞内游离钙离子浓度的主要途径,L 型钙通道中的α1亚单位(LTCCα1C)是决定 L 型钙通道电压依赖性和药物敏感性的重要部位。目的通过比较LTCCα1C亚基在正常大鼠和自发性高血压大鼠(SHR)胸主动脉 VSMC 表达的差异,以及经苯那普利和氟伐他汀干预后的变化.来阐明氟伐他汀、苯那普利抗高血压血管重构的分子机制。方法 12周龄雄性 SHR 24只,随机分为空白对照组(SHRc 组,n=8)、氟伐他汀治疗组[SHRf 组:20 mg/(kg·d),n=8]、苯那普利组[SHRb 组:10 mg/(kg·d),n=8],年龄和体质量匹配的 Wistar-Kyoto(WKY)大鼠为正常对照组(n=8)。灌胃法给药18周后苏木精一伊红染色计算胸主动脉血管壁/腔面积,RT-PCR 法、免疫组织化学法、Western blotting 法比较各组大鼠胸主动脉 LTCCα1C 的表达。结果 SHRc 组的胸主动脉壁腔面积比(壁/腔)与 WKY 组比较显著增高(0.30±0.01比WKY:0.1 9±0.02,P<0.05)。氟伐他汀和苯那普利降低大鼠胸主动脉的壁/腔(分别下降20.0%和33.3%)。SHRc 组胸主动脉的 LTCCα1C mRNA 的表达高于 WKY 组(0.56±0.02比 WKY:0.31±0.05,P<0.05),氟伐他汀和苯那普利降低 LTCCα1C 的 mRNA 表达(SHRf:0.42±0.03比 SHRb:0.38±0.03比 SHRc:0.56±0.02,P<0.05)。免疫组织化学方法与蛋白印迹法显示 SHRc 组大鼠胸主动脉 VSMC 中,LTCC α1C 蛋白表达强于 WKY 大鼠(0.25±0.04比 WKY:0.12±0.02,P<0.05),氟伐他汀和苯那普利降低 VSMC 内 LTCC α1C 的蛋白表达(SHRf:0.19±0.03比SHRb:0.17±0.02比 SHRc:0.25±0.04,P<0.05)。结论自发性高血压大鼠主动脉L型钙通道表达增强,氟伐他汀、苯那普利在抗高血压血管重构的同时改善胸主动脉平滑肌细胞 L 型钙离子通道α1C的重构效应。

Background L type calcium channel （LTCC） was known to be the major way to increase intracellular free calcium （[Ca^2＋ ]i） in vascular smooth muscle cells（VSMC）. The 1C subunit （LTCCα1C） functions as a voltage sensor, drug receptor, and Ca^2＋-seleetive transmembrance pore. Objective To investigate the differential expression of LTCCα1C in aortic VSMCs between spontaneously hypertensive rats （SHRs） and Wistar-Kyoto rats （WKYs）, and effects of benazepril and fluvastatin on the expression of LTCCα1C in VSMC in situ from thoracic aorta of SHR and possible underlining molecular mechanism. Methods Twenty-four 12-weeks-old male SHR were randomized to receive fluvastatin [SHRf： 20 mg/（kg·d）, n=8）, benazepril （SHRb： 10 mg/（kg·d）, n=8], or placebo （SHRc, n= 8） by gavage. Eight age and weight matched WKY rats served as controls（WKY, n= 8）. Rats were sacrified after 18-week treatment and ratio of wall-to-lumen area of thoracic aorta were assessed by morphormetric assay. L type calcium channel α1C mRNA and protein expression in thoracic aorta were determined by RT PCR, immunohistochemistry, and Western-blotting. Results The wall-to-lumen area ratio was significantly increased in SHRc as compared with WKY group （0.30±0.01 vs 0.19±0.02, P〈0.05）, fluvastatin or benazepril reduced the wall-to-lumen ratio by 20. 0% and 33.3% respectively. The expression of LTCCα1C mRNA in thoracic aorta of SHRc group was obviously higher as compared with that in WKY rats （0.56±0.02 vs 0.31±0.05, P〈 0. 05） and were markedly decreased by fluvastatin or benazepril treatment （0. 42 ± 0.03, 0. 38 ± 0.03 vs 0.56 ± 0.02, P〈0.05）. LTCCα1C protein was higher in SHRc group than in WKY rats（0. 25±0.04 vs WKY：0. 12±0. 02, P〈0.05）. Treatment with fluvastatin or benazepril significantly down-regulated LTCCα1C protein expression（HRf： 0.19-50.03 vs SHRb： 0.17±0.02 vs SHRc： 0.25±0.04, P〈0.05）. Conclusion Fluvastatin or benazepril treatment ameliorates L-type calcium channel α1C remodeling in VSMC of thoracic aorta from SHR.